docs: def setSignalHeader(self, edfsignal, channel_info):
          """
          Sets the parameter for signal edfsignal.
  
          channel_info should be a dict with
          these values:
  
              'label' : channel label (string, <= 16 characters, must be unique)
              'dimension' : physical dimension (e.g., mV) (string, <= 8 characters)
              'sample_rate' : sample frequency in hertz (int)
              'physical_max' : maximum physical value (float)
              'physical_min' : minimum physical value (float)
              'digital_max' : maximum digital value (int, -2**15 <= x < 2**15)
              'digital_min' : minimum digital value (int, -2**15 <= x < 2**15)
          """
          if edfsignal < 0 or edfsignal > self.n_channels:
              raise ChannelDoesNotExist(edfsignal)
          self.channels[edfsignal] = channel_info
          self.update_header()